The invention relates to an arrangement for obtaining an indication concerning an economical and/or uneconomical operation of a motor vehicle, with the use of a plurality of pick-ups or sensors which detect various operating factors, means for measuring and/or merely transmitting the detected operating factors to a device for the formation of values which characterize operating conditions, and means for indications of results of an evaluation of the formed operating condition values with the aid of a predetermined evaluation pattern.
When speaking of economical operation of a motor vehicle, particularly a truck or bus, this term generally relates today to the concept of performing a certain transportation task with the lowest possible, or in better words, only with the absolutely necessary, fuel requirement.
Of course, "absolutely necessary" refers to that fuel requirement which, aside from grave driving mistakes, results from a reasonable driving behavior, i.e. joining the flowing traffic and observing the recommended speeds, if the geographic conditions permit. For example, if a fully loaded truck has to climb a grade, this driving situation cannot generally be considered uneconomical because, in this case, an increased fuel requirement results not only from the driving of a distance but also from the inevitably required lifting work, and this requirement must be met for fulfilling the transportation task. It is essential that in these cases the driving behavior be adjusted to the principle of "absolutely necessary" which may make it necessary, for example, to shift and always to shift at the right time, or even to depress the gas pedal in certain cases.
Exceptions which require a correction of this basic evaluation of the "absolutely necessary" fuel requirement exist, for example, when relatively narrow time limits are set in the transportation of perishable goods or when the delivery and pick-up times or timetables of other means of transportation must be adhered to.
As is well known, in the past, it has been attempted to solve the problem of providing an indication of economical and/or uneconomical operation of a motor vehicle exclusively by measuring the momentary fuel consumption, i.e., by measuring the fuel amount consumed per distance or time unit or also, with the appropriate conversion, the distance which can be travelled per unit of amount of fuel. For this purpose, a plurality of direct and indirect measuring methods have become known, requiring, in part, highly complicated measuring techniques. It is further known to determine the absolute amounts of fuel consumed by counting and, if necessary, recording them and to use them later for the evaluation, for example, of the travel diagrams of tachographs, or for an economic evaluation for the determination of the costs related to a task. However, also in this method, highly complicated devices must be used if the errors of measurement are to be kept within reasonable limits, particularly because of the temperature variation which is inevitable in the operation of motor vehicles.
On the other hand, a momentary value indication of fuel consumption, which need not necessarily be based on a highly accurate flow measurement and which can be designed as an indication of a trend, offers the possibility to the driver to change his driving behavior in accordance with this indication. However, the driver is not relieved of having to interpret the indication for a given driving situation. Accordingly, aside from the fact that this indication is relatively unsteady and that damping measures must be provided, this indication leads to purely subjective changes of driving behavior which are made by feeling, as well as to a certain insecurity of the driver if, on the one hand, he seeks consistently to minimize the fuel requirement, and, on the other hand, he must adhere to recommended speeds and join the flowing traffic as much as possible in order not to become an obstacle. Moreover, an increase particularly of measuring devices in the motor vehicle indicating the momentary values which require a relatively long time to read and, thus, take the driver's attention from the traffic, leads to an increase of the safety risk. Accordingly, such a device will be ignored by a skilled driver because it is not useful in practice and, therefore, the device is meaningless.
A more accurate evaluation of the momentary operating condition of a motor vehicle than that possible by a mere indication of the fuel consumption can be achieved, for example, by means of an arrangement which has become known from German Offenlegungsschrift No. 2,357,770. This arrangement provides for an additional pointer which is coaxially arranged with the pointer of a speedometer and which is in operative gear connection with the gas pedal, so that the relation between the fuel supply controlled by the gas pedal and the momentary vehicle speed can be recognized. This combination of indications makes it possible to estimate whether it is possible by means of shifting to adjust the driving manner to a more advantageous fuel consumption/speed ratio. However, this combination must initially be directly interpreted by the driver. The above-mentioned reference only contains hints or suggestions for interpretation and, aside from the fact that no additional value which can be further processed is formed, cannot do justice to most of the critical operating conditions which occur in practical operation and often appear only to be uneconomical.
German Offenlegungsschrift No. 27 31 568, on the other hand, shows arrangement for the formation of an at least a qualitative indication concerning the momentary fuel consumption, wherein the throttle valve position and the speed threshold values are joined by means of a potentiometer in such a way that distinguishable indications of the fuel consumption can be obtained for the operation of a motor vehicle under load, when the vehicle overruns the engine, and during idling. Accordingly, this arrangement offers an actually obvious indication concerning the economical or uneconomical operation only with respect to the two conditions "idling" and "vehicle overrunning engine", and is just as unsuitable for the desired purpose, i.e. an indication concerning the economy of the driving condition, as the other known measuring devices for fuel consumption.
Another arrangement which has become known from German Offenlegungsschrift No. 28 07 604 essentially concerns the joining and indication of the operating factors "fuel consumption" and "acceleration," wherein the respective fuel consumption/acceleration ratio is indicated by means of a light-emitting diode matrix in the form of a light spot. Since, similarly to the first-mentioned German Offenlegungsschrift No. 23 57 770, the operating factors to be processed are either equal or equivalent, the essential operating conditions of a motor vehicle can only be insufficiently indicated by means of this arrangement. Therefore, the interpretation of the indication which, also in this case, is left to the driver, can lead to a completely incorrect adjustment of his driving manner. Aside from the requirements concerning the indicating means and the measuring device for the fuel consumption, the arrangement according to German Offenlegungsschrift 28 07 604 requires a significant observation effort of the driver, especially since the indication continuously changes during travel and, in many cases, the indication changes so quickly that a reaction of the driver to the indication is not even possible.
Since, accordingly, a mere indication of the fuel consumption, or also the combined indications from the state of the art, for evaluating the momentary operating condition of a motor vehicle, are either not suitable or only suitable to a limited extent, it is the task of the present invention to provide an arrangement which avoids the deficiencies of the already known solutions and, with the use of uncomplicated, yet distinctive measuring techniques, allows an indication which, on the one hand, offers an indication without interpretation concerning the economical and/or uneconomical operation of a motor vehicle, or at least signals severely uneconomical operating conditions, and, on the other hand, requires a minimum of attention by the driver for observation.
The solution of this task in accordance with the invention starts from the finding that momentary fuel consumption is not necessarily the decisive operating factor for indication concerning an economical or uneconomical operation of a motor vehicle, but that, on the contrary, the engine speed, which can be measured with much simpler means, provides an equivalent indication, at least as far as the actual operating condition of the engine is concerned. Furthermore, this indication is to be supplemented by the indication of another operating factor characterizing the condition of movement of the vehicle, for example, the acceleration or deceleration, so that also the physical factors influencing the condition of movement of the vehicle through geographic conditions, load and wind, are taken into consideration. In order to also take into consideration the subjective influence of the driver, it is necessary to also consider the momentary position of the gas pedal or an operating factor equivalent to the gas pedal position.
Consequently, the solution in accordance with the invention is characterized in that pick-ups or sensors are provided at least for detecting the speed of the engine, the distances travelled by the vehicle, and for detecting various gas pedal positions. A first comparator comprising means for selectively fixing threshold values is provided whose inputs are connected to the outputs of a speed measuring device assigned to the engine speed pick-up, and at whose outputs signals can be made available which, in accordance with the measured speed, characterize a speed range determined by the threshold values. A second comparator also comprising means for selectively fixing threshold values is provided whose inputs are connected to the outputs of an acceleration measuring device assigned to the distance pick-up and at whose outputs signals can be made available which, in accordance with the measured acceleration, characterize a certain acceleration range determined by the threshold values, but at least the ranges -.DELTA.b/O/+.DELTA.b,&gt;+.DELTA.b and &gt;-.DELTA.b. A matrix is formed in which the outputs of the first comparator, those of the second comparator, and the outputs of a gas pedal position pick-up are linked or encoded together in such a way that each is combined with all others, and that to the matrix there is connected at least one signal transmitter which provides a plurality of signal conditions of which a different one is assigned to each group of combined matrix outputs of equal ratings.
An embodiment of the invention provides that processing of the operating factors provided by the pick-ups is effected with the use of a microprocessor in such a way that a code word element characterizing the respective speed range is formed for each determined speed value, that a code word element characterizing the respective acceleration range is formed for each determined acceleration value, that, in addition, a code word element is formed for the respective position range of the gas pedal, and that the formed code word elements are OR'd in a working storage of the microprocessor to form a code word which generates an appropriate signal after further processing, with the content determined in accordance with the evaluation by a program stored in the arithmetic unit of the microprocessor.
Another embodiment of the invention provides that a plurality of indicating lights with different color representations are provided as signal transmitters, and/or that the signalling is effected in the form of verbal commands (e.g. shift gears, depress gas pedal), and that, simultaneously with the signalling, recording means including a tachograph are triggered.
Aside from the fact that, compared to the state of the art, only the arrangement in accordance with the invention in connection with the operating factors selected to be processed provides a pertinent indication which is specific for the operation. The invention, by means of the exclusive processing of operating factor ranges determined by threshold values, offers the advantage that relatively coarse tolerances are permissible at the pick-ups, i.e. at the points of detection of the operating factors. Moreover, the expenditure for the desired indication is kept low because of the finding that, for characterizing at least grossly uneconomical manners of driving, it is sufficient to determine only a few threshold values with a low number of operating factors. It is further advantageous that the pick-ups already provided in a truck or bus can be utilized for detecting the motor speeds and the distances travelled and only the position pick-ups required for the gas pedal or control rod must be provided. Therefore, a complicated measurement of the fuel consumption is avoided in all cases. Additionally, it is a special advantage in the driving routine that the driver is informed, for example, by signals of different colors, whether his driving manner is to be evaluated good or poor, possibly only conditionally satisfactory, and that these signals are possibly supplemented by verbal commands, such as, "depress gas pedal" or "shift gears". Signals of this kind do not require an interpretation and are easy to observe by the driver.
A special advantage is further provided in that, by "shifting" the threshold values, i.e. by enlarging or narrowing the operating factor ranges, it becomes possible in a relatively simple manner to obtain an evaluation which is specific for the vehicle, i.e. an adjustment of the evaluation pattern to the gear unit and the mechanical equipment of the respective vehicle. If necessary, the indication made possible by the three selected operating factors can be improved by a further division or by adding additional operating factors and, if applicable, the indication can be evaluated with different evaluation patterns.
Accordingly, the display of an evaluation of the operating conditions specific for the vehicle is important for the desired indication, and not the display of operating conditions as such, assuming that the latter have really been formed in a characterizing manner. Moreover, a skilled driver knows the operating conditions of his vehicle rather well; therefore, he does not require an indication of the individual conditions. However, the display of the evaluation of all the operating conditions enables him to take clear measures for maintaining or creating an economical manner of driving.
Of course, certain limit conditions must be set up in order to provide clear combinations corresponding to respective driving or operating conditions, and particularly for facilitating a meaningful evaluation for normal truck or bus operation. This includes the provision that an appropriate free area is ensured to the driver with respect to his driving manner. For example, it shall be predetermined that the lower range of the engine speed to be considered the control factor, i.e. the idling speed range, should not enter into the evaluation and, thus, a display should always only be effected during "travel" and a speed range of, for example, up to 60% of the rated speed of the engine is to be considered the optimum. In this connection, it is assumed initially that the skilled driver is well aware that the condition of idle operation is uneconomical with respect to the transportation task, but that he is forced to accept this condition at traffic lights and railroad gates. Another speed threshold value could then be predetermined, for example, at 85% of the rated speed. Furthermore, the optimum driving condition should be considered that driving condition during which the driving behavior of the vehicle can be characterized as "slightly drawing" with respect to the most favorable speed range. It must also be assumed initially that the driver is skilled and knows that he must shift into a lower gear if, for example, no more acceleration is possible by depressing the gas pedal and, consequently, the operating condition of the vehicle can no longer be called "slightly drawing."